From the past, there is known a vibration control device that generates a vibration control force by a vibration means and positively adding vibration to vibration of a vehicle that is caused by a fluctuation of an output torque of an engine of the vehicle, to thereby cancel the vibration of the vehicle. More specifically, as such a vibration control device, there is proposed a device including a linear actuator serving as a vibration means that is provided to an engine serving as a vibration generation source, means for detecting the rpm of the engine serving as the vibration generation source, a vibration detection means for detecting vibration at a position at which vibration is to be controlled, and an adaptive control algorithm with which a vibration command is output to the linear actuator provided between the engine and a vehicle body based on the detected rpm of the engine and the detected vibration at the position at which vibration is to be controlled (for example, see Patent Document 1). In this vibration control device, it is possible to output, by the adaptive control algorithm, a vibration command having an optimum amplitude and phase corresponding to the rpm of the engine and the vibration currently being detected at the position at which vibration is to be controlled, with the result that the vibration that is generated from the engine serving as the vibration generation source and is transmitted to the position at which vibration is to be controlled, such as a seat portion, can be reduced by a vibration control force generated from the vibration means.
In addition, there is known a vibration reducing device that makes, when a vehicle state changes between two vehicle states that are different in engine load, vibration levels substantially equal to each other around that change and prevents an occupant from feeling a sense of discomfort (see, for example, Patent Document 2). This device stores a vibration level obtained when the vibration within the vehicle is reduced by an operation of a vibration device at a time when large engine load is large, and controls the vibration device to make vibration close to the stored vibration level when the engine load is small. By performing the control as described above, it is possible to keep the vibration level equal even when the load of the engine is changed.
On the other hand, as a vibration means for reciprocating, there is known a linear actuator in which a mover is supported by an elastic support portion (plate spring) so as to be capable of reciprocating with respect to a stator (see, for example, Patent Document 3). In this linear actuator, since the mover is not worn, the accuracy of shaft support is not reduced even after a long period of use. Further, since slide resistance does not act on the mover, a loss of power consumption due to the slide resistance is small. Furthermore, since a bulky coil and the elastic support portion are arranged close to each other, it is possible to miniaturize the linear actuator.
The linear actuator disclosed in Patent Document 3 can cancel the vibration generated from a target device whose vibration is to be controlled, by a reaction force at a time of drive. In other words, the actuator can reduce the vibration of the vibration control target device by applying a current command so that the reaction force generated from the actuator has an opposite phase with respect to a vibration acceleration of the vibration control target device. It should be noted that the mover is generally given an auxiliary mass (weight) in order to increase the reaction force of the actuator. The vibration control device using such a linear actuator is attached to a vehicle body of an automobile, with the result that a force transmitted from an engine of the automobile to the vehicle body can be cancelled and thus the vibration of the vehicle can be reduced.
Patent Document 1: Japanese Patent Application Laid-open No. Hei 10-049204
Patent Document 2: Japanese Patent Application Laid-open No. Hei 08-261276
Patent Document 3: Japanese Patent Application Laid-open No. 2004-343964